Park on a slope with the front of the van higher, obviously.
Mix up some tile cleaner....
Tsunami seems to be the flavour of the month. ( mix half strength).
Put in small pump up, or trigger sprayer.
Apply chemical, scrub with stiff brush.
Rinse with HOT water, using your TM, with a pressure washing wand.
Apply double strength cleaning vinegar, full strength. Scrub again.
Rinse again.
Let dry.
Apply Aerospace 303, or the stuff Mike likes to use.....
PROBLEM SOLVED....
How do I know? Cause when mine gets white streaks, that’s what I do, and it looks brand new again....
Thank me later....